Came across this after completing a system update two days ago.

I run Radicale and that is refusing to start with the following error:

Traceback (most recent call last):
  File "/usr/bin/radicale", line 6, in <module>
    from pkg_resources import load_entry_point
  File "/usr/lib/python3.7/site-packages/pkg_resources/__init__.py", line 84, in <module>
    __import__('packaging.requirements')
  File "/usr/lib/python3.7/site-packages/packaging/requirements.py", line 9, in <module>
    from pyparsing import stringStart, stringEnd, originalTextFor, ParseException
ModuleNotFoundError: No module named 'pyparsing'

When attempting to run pip to see if that might correct the issue, I got the following error:

Traceback (most recent call last):
  File "/usr/bin/pip", line 6, in <module>
    from pkg_resources import load_entry_point
  File "/usr/lib/python3.7/site-packages/pkg_resources/__init__.py", line 84, in <module>
    __import__('packaging.requirements')
  File "/usr/lib/python3.7/site-packages/packaging/requirements.py", line 9, in <module>
    from pyparsing import stringStart, stringEnd, originalTextFor, ParseException
ModuleNotFoundError: No module named 'pyparsing'

It looks as though something recently broke pyparsing and that’s had a knockon effect for a few packages.